Over the past 50 years of automotive engineering, fuel injection has become the dominant system for mixing fuel with air for combusition in the engine cylinders. Early systems in the mid-1950's were mechanical in nature, but were supplanted in the 1960's and 1970's with various types of Electronic Fuel Injection, in large part due to the ability of EFIs to better achieve stoichiometric engine operation which reduced engine pollution. The closed loop systems introduced in the 80's improved the air/fuel mixture control by feed-back from an oxygen sensor located in the engine exhaust. Since that time, EFIs have continued to evolve and become more reliable, and except where there are no strict emission regulations, carburetor-controlled engines are the exception.
The fuel injector dispenses fuel directly into the engine air stream, typically being located in a port a few inches upstream of the intake valve of each cylinder, or directly into the cylinder itself. While the direct injection approach was initially used for diesel engines, gasoline engines now use direct injection. Typically, injectors employ a solenoid that is normally closed, that is a tapered tip of a solenoid plunger seats against a conical valve seat. The injectors are wired to an EFI control system microprocessor, and plumbed to the fuel lines. When the solenoid is energized by a signal from the EFI/DIS controller, the plunger is retracted and fuel under pressure is injected, passing through the valve seat and through an atomizer nozzle, thereby spraying fuel into the air stream passing through the port, or spraying fuel directly into the combustion chamber portion of the cylinder. In turn, the injector is connected to a high pressure fuel line, 40-50 psi for port fuel injection and 200-250 psi for direct injection. At these pressures, the fuel lines must be much more robust than the very low pressure that had been used for venturi-fed carburetor systems. This requirement led to the introduction of “fuel rails”, rigid pipes connected to a high pressure fuel line coming from the fuel tank via the high pressure fuel pump. The fuel rails are plumbed to the injectors.
Current fuel rails comprise simple exposed pipes or conduits that are cantilevered above the cylinder banks of the IC engine to which they are installed. For a V8 engine, two rails are provided, one for each bank of cylinders. They include a cross-over pipe that joins the fuel rails medially of their ends, and the inlet high pressure fuel line feeds into the cross-over pipe.
Thus, the current fuel rail design is an “H”-shape as seen in plan view from above, each of the long, vertical members representing a rail for one of the two cylinder banks, and the cross-bar representing the cross-over pipe. The fuel from the fuel pump feeds into the center of the cross-bar of the “H”-shaped design. This “H” design routes the fuel over the engine, thus presenting service technicians with a line that can be in the way of other work, and if snagged, can result in breakage of seals with attendant leakage of fuel. In addition, there is little if any flex in the cross-over pipe, so the current assembly has to be aligned with, in a V8 engine, eight spaced injectors or injector ports in both cylinder heads simultaneously, a task that is not easy.
The current type of fuel rail assembly is secured to the engine only via the injectors; that is, the injectors themselves serve as the support pillars. Bumping the rails can break the injector seals causing dangerous fuel leaks on hot engine parts during operation, in part because the rails are of low mass, and do not have sufficient inertia to absorb a bump or jostle. The net result is that the rails, the fuel line, the cross-over pipe, and the wiring from the EFI/DIS controller(s) and power supply to the injectors can come into contact with various other engine parts, and present complex, overlapping parts that must be properly routed and carefully kept clear-of during servicing.
In addition to the wiring currently being essentially loose and exposed, the insulation and its support or retainer brackets on the inner surface of the hood can come into contact with the wiring when the hood is closed, pressing down on the wiring. This can lead to two problems: First, rubbing wear on the wiring that can cause breaks or change in conductive properties of the wiring; Second, there is a potential for pressing the wiring down onto hot surfaces of the engine below the wiring. In addition, exposed wiring can become snagged during servicing.
Accordingly, there is an unmet need in the art for an assembly that protects wiring and better routes fuel lines while at the same time is robust, more massive, and attractive.